In the European Patent Application No. 0,172,937, the British Patent Applications Nos. 2,031,767 and 2,245,204 and the Soviet Invention Description No. 1,090,489, methods are disclosed, in which to begin with solely the first squeeze member is moved, upon which the second squeeze member is moved when some parameter relating to the mold chamber has reached a predetermined value. According to these publiccations, the parameter is constituted by or depends on the length of the path of movement carried out by the first squeeze member during the compacting operation. Thus, the control of the initiation of the movement of the second squeeze member is not based on sensing parameters expressing the instantaneous state of the particulate material, e.g. mold sand, having compacted during the first stage of the compacting process, i.e., during the period in which only the first squeeze member moves.